Missions to asteroid Apophis in 2029.

[selvaarchi]

There are no know missions I know of that are planned to visit this asteroid in 2029 but I am guessing there will be. Three reasons. This not a small asteroid but one the is over 1,000 feet across. The other reason is in 2029 it will be so close to earth that it will pass through some of the satellites that are in high orbit and would also be a naked eye object. So any mission planned to visit it will take days not years to reach it.

https://www.popularmechanics.com/spa...id-flyby-2029/

A decade from now, on April 15, 2029, an asteroid will swing past the Earth, just barely missing everything. The asteroid—nicknamed Apophis—will be as close as some of our satellites and only a few thousand miles away from the Earth’s atmosphere itself. That would make it one of the closest near-miss asteroids in history, and an incredible chance for scientists to learn as much as they can about it.

[publiusr]

I wonder if any of the more northerly Russian Molniya orbits allow for things to get really close.

[Roger E. Moore]

What if asteroid Apophis decides to get TOO close? A paper suggests throwing rocks at it. Big space rocks.

https://arxiv.org/abs/1907.11087

Enhanced Kinetic Impactor for Deflecting Large Potentially Hazardous Asteroids via Maneuvering Space Rocks
Mingtao Li, Yirui Wang, Youliang Wang, Binghong Zhou, Wei Zheng
(Submitted on 24 Jul 2019 (v1), last revised 10 Mar 2020 (this version, v2))

Asteroid impacts pose a major threat to all life on Earth. The age of the dinosaur was abruptly ended by a 10-km-diameter asteroid. Currently, a nuclear device is the only means of deflecting large potentially hazardous asteroids (PHAs) away from an Earth-impacting trajectory. The Enhanced Kinetic Impactor (EKI) concept is proposed to deflect large PHAs via maneuvering space rocks. First, an unmanned spacecraft is launched to rendezvous with a near-Earth asteroid (NEA) that passes close to the target PHA. Then, hundreds of tons of rocks are collected from the NEA as an enhanced impactor. The NEA can also be captured as an enhanced impactor if the NEA is very small. Finally, the enhanced impactor is maneuvered to impact the PHA at a high speed, resulting in a significant deflection of the PHA. For example, to deflect Apophis, as much as 200 t of rocks could be collected from an NEA as an enhanced impactor based on existing engineering capabilities. The EKI could produce a delta-v of 39.93 mm/s in Apophis, thereby increasing the minimum geocentric distance during the close encounter in 2029 by 1,989.27 km. This mission could be completed in 3.9 years, with a fuel cost of 2.73 t. The momentum transferred to the Apophis by the EKI is two orders of magnitude higher than that of the classic kinetic impact strategy. With the existing engineering capabilities, the EKI concept can be used to effectively deflect large PHAs. We anticipate that our research will be a starting point for efficient planetary defense against large PHAs.

[Roger E. Moore]

Will passing so close to Earth cause tidal-force problems for asteroid Apophis in 2029?

https://arxiv.org/abs/1803.05375

Surface Composition of (99942) Apophis
Vishnu Reddy, Juan Sanchez, Roberto Furfaro, Richard Binzel, Thomas Burbine, Lucille Le Corre, Paul Hardersen, William Bottke, Marina Brozovic
(Submitted on 14 Mar 2018)

On April 13, 2029, near-Earth asteroid (NEA) (99942) Apophis will pass at a distance of 6 Earth radii from Earth. This event will provide researchers with a unique opportunity to study the effects of tidal forces experienced by an asteroid during a close encounter with a terrestrial planet. Binzel et al. (2010) predicted that close flybys of terrestrial planets by NEAs would cause resurfacing of their regolith due to seismic shaking. In this work we present the best pre-encounter near-infrared spectra of Apophis obtained so far. These new data were obtained during the 2013 apparition using the NASA Infrared Telescope Facility (IRTF). We found that our spectral data is consistent with previous observations by Binzel et al. (2009) but with a much higher signal-to-noise ratio. Spectral band parameters were extracted from the spectra and were used to determine the composition of the asteroid. Using a naive Bayes classifier, we computed the likelihood of Apophis being an LL chondrite to be >99% based on mol% of Fa vs. Fs. Using the same method, we estimated a probability of 89% for Apophis being an LL chondrite based on ol/(ol+px) and Fs. The results from the dynamical model indicate that the most likely source region for Apophis is the nu6 resonance in the inner main belt. Data presented in this study (especially Band I depth) could serve as a baseline to verify seismic shaking during the 2029 encounter.

[Roger E. Moore]

"David Tholen, an astronomer at the University of Hawaii, recently reported on the status of asteroid Apophis during a virtual meeting of the American Astronomical Society's Division for Planetary Sciences. During his presentation, he outlined research he and his team conducted regarding the path of the asteroid and the likelihood that it will strike Earth. The asteroid Apophis was first spotted by astronomers back in 2004. Shortly thereafter, researchers worked out its orbital path and found that the 340-meter-wide asteroid would pass near to the Earth in 2029, 2036 and again in 2068. More study showed that there was little chance of the asteroid striking Earth; thus, it was discounted as a threat. More recently, Tholen and his team noted that earlier researchers had not accounted for the Yarkovsky effect by which rays from the sun strikes one side of an asteroid. As the heat radiates away from the asteroid, a small amount of energy pushes back against the asteroid, forcing it to turn slightly. Tholen and his team calculated that the Yarkovsky effect is pushing Apophis to one side enough to force it to drift by approximately 170 meters a year. They next applied that bit of knowledge to the math describing Apophis's orbit and found that the drift is changing the course of the asteroid in a way that will bring it closer to Earth. He notes that thus far, there is no indication that the asteroid will strike the Earth in 2029 and 2036, but 2068 might be another matter. He suggests that astronomers will have to keep an eye on Apophis as its rendezvous date approaches."

https://phys.org/news/2020-11-apophi...h-thought.html

[Roger E. Moore]

Impact chances with Apophis still very small despite influence of Yarkovsky effect.


https://arxiv.org/abs/2011.13632

Impact Probability Under Aleatory And Epistemic Uncertainties

C. Tardioli, D. Farnocchia, M. Vasile, S. R. Chesley

We present an approach to estimate an upper bound for the impact probability of a potentially hazardous asteroid when part of the force model depends on unknown parameters whose statistical distribution needs to be assumed. As case study we consider Apophis' risk assessment for the 2036 and 2068 keyholes based on information available as of 2013. Within the framework of epistemic uncertainties, under the independence and non-correlation assumption, we assign parametric families of distributions to the physical properties of Apophis that define the Yarkovsky perturbation and in turn the future orbital evolution of the asteroid. We find IP≤5×10−5 for the 2036 keyhole and IP≤1.6×10−5 for the 2068 keyhole. These upper bounds are largely conservative choices due to the rather wide range of statistical distributions that we explored.

[Roger E. Moore]

Mission planning to meet near-Earth asteroid Apophis is underway.

https://arxiv.org/abs/2012.06781

First approximation for spacecraft motion relative to (99942) Apophis

S. Aljbaae, D. M. Sanchez, A. F. B. A. Prado, J. Souchay, M. O. Terra, R. B. Negri, L. O. Marchi

We aim at providing a preliminary approach on the dynamics of a spacecraft in orbit about the asteroid (99942) Apophis during its Earth close approach. The physical properties from the polyhedral shape of the target are derived assigning each tetrahedron to a point mass in its center. That considerably reduces the computation processing time compared to previous methods to evaluate the gravitational potential. The surfaces of section close to Apophis are build considering or not the gravitational perturbations of the Sun, the planets, and the SRP. The Earth is the one that most affects the invisticated region making the vast majority of the orbits to collide or escape from the system. Moreover, from numerical analysis of orbits started on March 1, 2029, the less perturbed region is characterized by the variation of the semimajor axis of 40-days orbits, which do not exceed 2 km very close to the central body (a<4 km, e<0.4). However, no regions investigated could be a possible option for inserting a spacecraft into natural orbits around Apophis during the close approach with our planet. Finally, to solve the stabilization problem in the system, we apply a robust path following control law to control the orbital geometry of a spacecraft. At last, we present an example of successful operation of our orbit control with a total △v of 0.495 m/s for 60 days. All our results are gathered in the CPM-ASTEROID database, which will be regularly updated by considering other asteroids.